title: Reaction of alpha-tocopherol in heated bulk phase in the presence of methyl linoleate (13S)-hydroperoxide or methyl linoleate.
abstract: alpha-Tocopherol and methyl (9Z,11E)-(S)-13-hydroperoxy-9,11-octadecadienoate (13-MeLOOH) were allowed to stand at 100 degrees C in bulk phase. The products were isolated and identified as methyl 13-hydroxyoctadecadienoate (1), stereoisomers of methyl 9,11,13-octadecatrienoate (2), methyl 13-oxo-9,11-octadecadienoate (3), epoxy dimers of methyl linoleate with an ether bond (4), a mixture of methyl (E)-12,13-epoxy-9-(alpha-tocopheroxy)-10-octadecenoates and methyl (E)-12,13-epoxy-11-(alpha-tocopheroxy)-9-octadecenoates (5), a mixture of methyl 9-(alpha-tocopheroxy)-10,12-octadecadienoates and methyl 13-(alpha-tocopheroxy)-9,11-octadecadienoates (6), alpha-tocopherol spirodiene dimer (7), and alpha-tocopherol trimer (8). alpha-Tocopherol and 13-MeLOOH were dissolved in methyl myristate, and the thermal decomposition rate and the distributions of reaction products formed from alpha-tocopherol and 13-MeLOOH were analyzed. alpha-Tocopherol disappeared during the first 20 min, and the main products of alpha-tocopherol were 5 and 6 with the accumulation of 1-4 which were the products of 13-MeLOOH. The results indicate that the alkyl and alkoxyl radicals from the thermal decomposition of 13-MeLOOH could be trapped by alpha-tocopherol to produce 5 and 6. The reaction products of alpha-tocopherol during the thermal oxidation of methyl linoleate were compounds 6 and 7. Since the radical flux during the autoxidation might be low, the excess alpha-tocopheroxyl radical reacted with each other to form 7.
authors.affiliation: Department of Food Science, Faculty of Agriculture, Gifu University, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Yamauchi
authors.forename: K
authors.initials: K
authors.lastname: Goto
authors.forename: K
authors.initials: K
authors.lastname: Kato
mesh_terms: D002851:Chromatography, High Pressure Liquid; D019281:Dimerization; D004355:Drug Stability; D005609:Free Radicals; D006358:Hot Temperature; D007700:Kinetics; D008041:Linoleic Acids / Q000737:chemistry*; D008054:Lipid Peroxides / Q000737:chemistry*; D010084:Oxidation-Reduction; D013237:Stereoisomerism; D014810:Vitamin E / Q000737:chemistry*
chemical_list: D005609:Free Radicals; D008041:Linoleic Acids; D008054:Lipid Peroxides; C008464:methyl linoleate hydroperoxide; D014810:Vitamin E; C005575:methyl linoleate